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extern crate proc_macro;
extern crate proc_macro2;

extern crate syn;
use syn::parse_macro_input;

extern crate quote;
use quote::ToTokens;


// PEG paper: http://bford.info/pub/lang/peg.pdf

mod parser;
mod codegen;

// TODO: rewrite AST enum to facilitate `impl Parse` for each variant
// TODO: support for using external non-terminals (i.e. other nom based parsers)
// TODO: parser templates maybe? (like lalrpop)
// TODO: extra functionality
//   - character classes `[a-zA-z]`
//   - any character, `.`
//   - repetition: exactly n times `{n}`, n or more times `{n,}`, at least n and at most m times `{n, m}`
//   - more regex features?
//   - handle named captures inside looping constucts

// TODO: option to skip whitespace

#[proc_macro]
pub fn grammar(tokens: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let parse_tree = parse_macro_input!(tokens as parser::ParseTree);
    // eprintln!("!! input: {:?}", parse_tree);

    parse_tree.into_token_stream().into()
}